Integrated circuits, or ICs, are created by patterning a substrate and materials deposited on the substrate. The substrate is typically a semiconductor wafer. The patterned features make up devices and interconnections. This process generally starts with a designer creating an integrated circuit by hierarchically defining functional components of the circuit using a hardware description language. From this high-level functional description, a physical circuit implementation dataset is created, which is usually in the form of a netlist. This netlist identifies logic cell instances from a cell library, and describes cell-to-cell connectivity.
Many phases of these electronic design activities may be performed with computer aided design (CAD) tools or electronic design automation (EDA) systems. For example, an integrated circuit designer may use a set of layout EDA application programs, such as a layout editor, to create a physical integrated circuit design layout from a logical circuit design. The layout EDA application uses geometric shapes of different materials to create the various electrical components on an integrated circuit and to represent electronic and circuit IC components as geometric objects with varying shapes and sizes. After an integrated circuit designer has created an initial integrated circuit layout, the integrated circuit designer then verifies and optimizes the integrated circuit layout using a set of EDA testing and analysis tools. Verification may include, for example, design rule checking to verify compliance with rules established for various IC parameters. The EDA layout editing tools are often performed interactively so that the designer can review and provide careful control over the details of the electronic design.
Typically, geometric information about the placement of the nodes and components onto the chip is determined by a placement process and a routing process. The placement process is a process for placing electronic components or circuit blocks on the chip and the routing process is the process for creating interconnections between the blocks and components according to the specified netlist. The task of all routers is the same—routers are given some pre-existing polygons consisting of pins on cells and optionally some pre-routes from the placers to create geometries so that all pins assigned to different nets are connected by wires and vias, that all wires and vias assigned to different nets do not overlap, and that all design rules are obeyed. That is, a router fails when two pins on the same net that should be connected are open, when two pins on two different nets that should remain open are shorted, or when some design rules are violated during routing.
A layout file is created from the placement and routing process, which assigns logic cells to physical locations in the device layout and routes their interconnections. The physical layout is typically described as many patterned layers, and the pattern of each layer is described by the union of a set of polygons. The layout data set is stored, for example in GDSII (“Graphic Data System II”) or OASIS (“Open Artwork System Interchange Standard”) formats. Component devices and interconnections of the integrated circuit are constructed layer by layer. A layer is deposited on the wafer and then it is patterned using a photolithography process and an etch process.
Traditionally, track patterns include parallel tracks with uniform pitches, and the tracks cover entire layout space. This conventional approach does not satisfy the needs for electronic layout with a typical half-pitch of 14 nm or below. With the typical half-pitch advancing to 14 nm or below, the track patterns for a certain metal layer may be required or desired to be region-based where one track pattern may be associated with or assigned to a region on one layer, while another track pattern may be associated with or assigned to another region on the same layer. Some designs may even demand or desire non-uniform track patterns. Conventional approaches do not allow periodic changes of track pitches and definitions of regions where one or more track patterns are active. These track pattern requirements pose a challenge for physical design implementation, especially for interactive layout editing. In addition, users may need to interactively define track pattern(s) during the chip floorplanning or placement stage and follow such track pattern(s) during subsequent physical design stages such as routing, post-layout optimization, engineering change order (ECO), or even specific physical design tasks such as wire editing.
In addition, advanced manufacturing processes have imposed new requirements on electronic designs. For example, certain manufacturing processes require that wires on certain layers (e.g., metal 1 layer, metal 2 layer, etc.) are to be on certain routing tracks (e.g., subject to on-track requirements), while wires on certain other layers (e.g., metal 5 layer, metal 6 layer, etc.) may be physically implemented (e.g., through placement or routing processes) without track requirements. Some manufacturing processes may further require that certain regions on a routing layer be subject to some on-track requirements, while another region (or another regions) are not subject to any on-track requirements.
Thus, there exists a need for methods, systems, and articles of manufacture for implementing electronic design using flexible routing tracks.